A Nuclear Atom Flashcards
who was the first person who essentially discovered the basic model for the atom
john dalton
what did dalton state about the atom
- it was simply a hard solid sphere
- that was indestructible / couldnt be further broken down
what model did thompson come up with for the atom
the plum pudding model
what did he discover about the atom for him to come up with the model
- that there are negatively charged electrons that could be removed from an atom
- leaving a spread out positively charged ion
what was the plum pudding model like
- a positively charged sphere (the dough)
- with the negatively charged electrons scattered within it (the plums)
who was the first person to come up with the nuclear model of the atom
rutherford
what did his model state
- that there was a tiny charged nucleus at the centre
- which had a concentrated positive charge
- surrounded at some distance by electrons
what experiment did rutherford carry out to come up with this model and what did it consist of
- the alpha particle scattering experiment
- he shot alpha particles at a thin sheet of gold
- and detected where the alpha particle emerged with detectors surrounding the sheet
what observation of this experiment caused him to think that there was a strong concentrated positive charge
- some of the alpha particles were being deflected over 90 degrees
- some of those being directly back at him
- suggesting there strong electrostatic repulsion between the particle and something in the atom
what observation caused him to think that most of an atom was empty space
- most of the alpha particles passed straight through without being deflected or barely being deflected
- suggesting that most of the gold sheet consisted of empty space
what did both of those conclusions lead rutherford to suggest
- that there was a tiny nucleus with a strong, concentrated +ve charge
- with its electrons surrounding it being a good distance away from it (relative it their size)
who was the person who further refined rutherford’s nuclear model of the atom
niel bohr
what did he discover about the atom
- that electrons exist in fixed orbits (certain well defined energy levels)
- and that they could quantum leap from one energy level to the other
- if they absorbed / emitted the right amount of energy at once
what was this theory / model of the atom called
the quantum theory / model
what did chadwick discover
the neutron
what are protons and neutrons in a nucleus collectively called
nucleons
past an atomic number of 20, what does the relationship between the number of protons and neutrons need to be in order for the atom to remain stable
there generally needs to be more neutrons than protons in the nucleus
what are the 2 reasons for there to be more neutrons than protons in order for it to remain stable
- the neutrons help bind the nucleus together as they exert a strong electrostatic force on other nucleons
- they also act as a space buffer between the mutually repelling positive charges of the protons within a nucleus
how does the ratio of neutrons to protons change as the number of protons increases
- there will be an increasing amount of neutrons per increase of protons
- similar to a y = x^2 relationship
although the quantum model of the atom is pretty accurate, why is the solar system-like model of the orbiting electrons practically wrong
because you cant know the position and velocity of an electron at the same time
what is that idea called
the uncertainty principle
what was the new model that was created in order to take this into account
- instead of specific orbits, atoms had regions of space around them called probability clouds
- these were regions where there was a high probability (90%) of finding an electron in them
thinking back to chemistry, what are these probability clouds called
orbitals
